Systematic (IUPAC) name | |
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(6R,7R)-7-{[(2R)-2-amino-2-phenylacetyl]amino}- 3-methyl-8-oxo-5-thia-1-azabicyclo[4.2.0]oct-2-ene- 2-carboxylic acid | |
Clinical data | |
AHFS/Drugs.com | International Drug Names |
Pregnancy cat. | A(AU) B(US) |
Legal status | Prescription Only (S4) (AU) POM (UK) |
Routes | Oral |
Pharmacokinetic data | |
Bioavailability | Well absorbed |
Protein binding | 15% |
Metabolism | 80% excreted unchanged in urine within 6 hours of administration |
Half-life | For an adult with normal renal function, the serum half-life is 0.5-1.2 hours[1] |
Excretion | Renal |
Identifiers | |
CAS number | 15686-71-2 |
ATC code | J01DB01 QJ51DA01 |
PubChem | CID 2666 |
DrugBank | APRD00250 |
ChemSpider | 25541 |
UNII | 5SFF1W6677 |
KEGG | D00263 |
ChEBI | CHEBI:3534 |
ChEMBL | CHEMBL1727 |
Chemical data | |
Formula | C16H17N3O4S |
Mol. mass | 347.39 g/mol |
SMILES | eMolecules & PubChem |
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Cefalexin (INN) or more commonly cephalexin ( /ˌsɛfəˈlɛksɨn/) is a first-generation cephalosporin antibiotic introduced in 1967 by Eli Lilly and Company.[2][3] It is an orally administered agent with a similar antimicrobial spectrum to the intravenous agents cefalotin and cefazolin. It was first marketed as Keflex (Lilly), and now is also sold under several other trade names.[2]
As of 2008, cefalexin was the most popular cephalosporin antibiotic in the United States, with more than 25 million prescriptions of its generic versions alone, for US$255 million in sales (though less popular than two other antibiotics, amoxicillin and azithromycin, each with 50 million prescriptions per year).[4][5]
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Cefalexin is used to treat a number of infections including: otitis media, streptococcal pharyngitis, bone and joint infections, pneumonia, cellulitis, and urinary tract infections.[6] It may be used to prevent bacterial endocarditis.[6]
In addition to being a rational first-line treatment for cellulitis, it is a useful alternative to penicillins in patients with penicillin hypersensitivity. In patients with mild or questionable history of penicillin allergy, cephalasporins are now thought to be relatively safe.[7] Caution should always be taken when prescribing cephalosporins to those with strong history of true penicillin hypersensitivity, however, because cefalexin and other first-generation cephalosporins are known to have a modest cross-allergy in patients with penicillin hypersensitivity.
Cefalexin may not be effective against bacteria that incorporate a gene for beta-lactamase on their R-plasmid as the beta-lactam ring is present in the chemical structure of cephalosporin derivatives.
Cefalexin is marketed by generic pharmaceutical manufacturers under a wide range of brand names, including: Apo-Cephalex, Biocef, Cefanox, Ceforal, Cephabos, Cephalexin, Cephorum, Ceporex, Cilex, Ialex, Ibilex, Kefexin, Keflet, Keflex, Rekosporin, Keforal, Keftab, Keftal, Lopilexin, Larixin, Novo-Lexin, Ospexin, Tenkorex, Zephalexin, Panixine Disperdose, and Sporidex.
A version of Keflex 750 mg capsules is marketed for twice-daily dosage, to improve compliance. However, it is not a sustained release formulation, and since it is more expensive than the older strengths, some physicians prescribe three 250 mg capsules to be taken twice daily, as a cheaper alternative.
In Finland, cefalexin is marketed under several names. Orion markets Kefexin.[8][9]
Adverse effects from cefalexin include diarrhea, dizziness, agitation, headache, indigestion, joint pain, stomach pain (usually mild) and tiredness. The drug can also cause yellowing of the eyes or skin; red, blistered, swollen or peeling skin; unusual bruising or bleeding; decreased urination; severe cramps and confusion. An allergic reaction to this medicine is unlikely. Symptoms of an allergic reaction include rash, itching, swelling, or trouble breathing.